EP0291094A1 - Progressive power ophtalmic lens - Google Patents

Abstract

PCT No. PCT/DE88/00286 Sec. 371 Date Jan. 11, 1989 Sec. 102(e) Date Jan. 11, 1989 PCT Filed May 14, 1988 PCT Pub. No. WO88/08994 PCT Pub. Date Nov. 17, 1988.A progressive power ophthalmic lens having at least one surface contributing to an increase in power from a distant portion via a progressive zone to a reading portion, radii of curvature of horizontal section curves of the at least one surface contributing to an increase in power and having horizontal planes as a function of the distance from the main meridian decrease in a front surface in the region of the main meridian in the distant portion and increase in the rear surface in the distant portion and decrease in the reading portion, and the course of change of the curvature DELTA rh-rh(x,y)-rh (0,y) reverses with increasing distance x from the main meridian.

Description

Technical field

The invention relates to a progressive spectacle lens in which at least one surface contributes to the increase in effectiveness from the far part via the progression zone to the near part, and in which the radii of curvature of the cutting curves (horizontal cuts) of the surface contributing to the increase in effect or surfaces with horizontal planes as a function of the distance from Decrease the skin meridian on the front surface in the area of the main meridian in the far part and increase it in the near part and increase it on the eye surface in the far part and decrease it in the far part, and the course of the curvature change reverses with increasing distance from the main meridian.

State of the art

In the case of progressive spectacle lenses, there is generally the problem that the progression, that is to say the increase in the refractive index on the main meridian, leads to a sharp increase in the astigmatism and the distortion in the peripheral regions due to the intersections resulting from the continuity conditions of the surface.

Therefore, it has already been proposed in US Pat. No. 2,878,721 to increase the curvatures of the orthogonal or horizontal sections in the distant part at the front surface with increasing distance from the main meridian and to let it decrease in the near part. According to this document, there is a circular cut between the far and near parts as a transition from the area in which the radii of curvature increase to the area in which the radii of curvature decrease. This concept leads to the fact that the differences between the far and near parts in the edge area decrease, so that there are also smaller image errors and in particular smaller area astigmatism and distortion values.

A disadvantage of this known concept, however, is that the lines of the same refractive index are curved upwards in the vicinity of the main meridian and downwards in the near part, so that the lines of the same refractive index do not run horizontally. In order to reduce the curvature of the lines with the same refractive index upwards or downwards, it has therefore already been proposed in US Pat. No. 2,878,721 that the course of the change in curvature of horizontal or orthogonal sections reverses with increasing distance from the main meridian.

This concept described in US Pat. No. 2,878,721 for changing the radii of curvature of horizontal sections or the orthogonal sections in the area of the main meridian, the course of which is essentially the same as the course of the horizontal sections, is described in DE-AS 20 44 639, DE- OS 30 16 935 and DE-OS 31 51 766 have been adopted.

Despite the reversal of the course of the change in curvature of the horizontal or orthogonal sections, the known surfaces have the disadvantage that the lines are the same surfaces refractive index, particularly in the progression area on both sides of the main meridian.

Presentation of the invention

The invention is based on the object of specifying a progressive spectacle lens in which the lines of the same refractive index run largely horizontally at least in the area of the main meridian.

A solution to this problem according to the invention is characterized by its developments in the claims.

Surprisingly, a solution to this problem is achieved by starting from a spectacle lens according to the preamble of claim 1 and selecting the area so that the course of the change in curvature of the horizontal sections increases with distance from the main meridian by superimposing two functions F 1 (x, y) and F₂ (x, y) is given. According to the first function F 1 (x, y), the radius of curvature at the front surface initially increases or at the eye-side surface, the change in the radius of curvature being reversed at a distance of approximately 14 to 26 mm from the main meridian. According to the second function F₂ (x, y), the radius of curvature initially decreases on the front surface and increases on the surface on the eye side, the change in the radius of curvature also reversing at a distance of approximately 14 to 26 mm from the main meridian. The two functions are now superimposed in such a way that the absolute values of the amplitudes of the two functions change in opposite directions along the main meridian, at least in the progression zone. Furthermore, the functions F₁ and F₂ differ in their slope, which is larger in the second function in the area of the main meridian.

This inventive design of the two functions leads to areas in which the proportion of a function predominates, and on the other hand to areas in which both functions influence the design of the progressive surface differently.

This design according to the invention "decouples" the transition between the far part and the near part in the area of the main meridian and the corresponding transition in the areas spaced from the main meridian. This affects compromises that may in the edge area are not necessary, the surface design in the vicinity of the main meridian, i.e. in the part that serves to clearly see. In other words, the area with different main meridian coordinates shows the transition from long-distance to near-part properties for the area around the main meridian or the area spaced from the main meridian.

Through this design of the progressive surface characterized in claim 1 or when using a spectacle lens with two progressive surfaces at least one of the two progressive surfaces, a glass is obtained in which the surface astigmatism, which is known per se in the peripheral areas and in particular in the lateral lower edge areas is concentrated, is equal to or smaller than most glasses according to the prior art. In addition, the change in astigmatism is smaller than in the case of glasses according to the prior art. Above all, however, at least in the area of the main meridian, the spectacle lens according to the invention has an approximately horizontal course of the lines with the same refractive index or the lines with the same effect.

These properties of the progressive spectacle lens according to the invention are a result of the superimposition of two functions, by means of which there is an area adaptation or a surface transition from the far part to the near part in the lateral areas, which does not cause any disturbing aberrations or rocking movements for the spectacle wearer due to incompatible distortion etc. leads. In particular, the surface design according to the invention enables a surface correction in the periphery to be largely independent of that in the vicinity of the main meridian; this is a prerequisite for the advantageous properties mentioned.

The progressive areas according to the invention also have the advantage that their calculation is possible with comparatively little effort, so that they can be calculated separately for each distance effect and each addition. In the prior art, however, only an area is actually calculated. The other areas are then derived from this area by "similarity transformations". A little further explanation is required, which may result in poorer properties.

Developments of the invention are specified in the subclaims.

It is particularly advantageous if, in accordance with claim 2, the opposite change in the absolute values of the amplitudes of the two functions is such that the amplitude of the second function is maximal in the far part and almost or equal to zero in the near part. Due to this change in the amplitude of the second function, it is only effective in the far part and in the upper area of the progression zone, not however in the lower part of the progression zone and in the near part.

On the other hand, it is particularly advantageous for the first function if its maximum amplitude first increases from the lower edge of the spectacle lens to a maximum value in the region of the near reference point and then decreases to a value in the region of the distant part that remains at comparatively small values> 0 . The first function is therefore not only important in the near part and in the lower part of the progression zone, but also in the far part and in the upper part of the progression zone.

Characterized in claims 2 and 3, special opposite variation of the amplitudes of the two functions F₁ and F₂ leads to a particularly well-balanced area in the lateral edge areas, in which the distant part with its special characteristics without disturbing astigmatism accumulation or astigmatism jumps continuously ignores the near part.

The structure according to the invention results in areas which differ significantly from the known areas:

For example, an advantageous development is characterized in claim 4, in which the radius of curvature initially changes due to the superimposition of the two functions F 1, F 2 with different slope in the area to the side of the main meridian, but then remains almost constant over a larger area. This variation behavior of the radii of curvature contrary to the state of the art and in particular the teaching of DE-OS 31 47 952 leads to a large and almost astigmatism-free Far part (surface astigmatism <0.5 D and in particular <0.25 D) can be realized without disturbing the lateral part of the transition zone.

Furthermore, it is particularly advantageous if the maximum amplitudes of the two functions differ greatly, in other words if the variation in the radii of curvature is comparatively strong in the near part, but comparatively small in the distant part.

A further property of the spectacle lens according to the invention is that, in contrast to the state of the art of Tecknik, there is no roughly circular cut either in the horizontal or in the orthogonal section. On the contrary, in the transition zone, which according to the state of the art of Tecknik generally has an at least approximately circular section, an apparently sinusoidal variation of the radius of curvature results with comparatively large amplitudes as a function of the distance from the main meridian. In particular, it is a characteristic of an advantageous further development of the invention that the remote part, which has a large area with small astigmatism values compared to the prior art, is nevertheless not spherical (claim 10).

In contrast to the prior art, even the values of the radii of curvature can initially be smaller and then larger than on the main meridian or vice versa. However, it is particularly advantageous if - as characterized in claim 8 - the radii of curvature of horizontal sections 8n of the progression zone increase with increasing distance from the main meridian or initially smaller and then larger than on the main meridian or initially larger and then approximately the same size as on the main meridian.

Furthermore, it can be characteristic of the spectacle lens according to the invention that the reversal of the change in curvature does not take place at a constant distance from the main meridian, but that the distance of the point from the main meridian at which the change in curvature reverses the function to the lower edge of the spectacle lens decreases.

The basic principles of the invention can of course be applied to any spectacle lenses with one or two progressive surfaces and also to spectacle lenses whose main meridian is curved or flat. A particularly simple construction results, however, if the main meridian is flat.

Brief description of the drawing

• Fig. 1 den Flächenbrechwert eines erfindungsgemäßen Brillenglases längs des Hauptmeridians,
• Fig. 2.01 bis 2.17 die Krümmungsradien von Horizontal­schnitten als Funktion des Abstandes vom Haupt­meridian,
• Fig. 3 die Änderung des Maximalwertes der Funktionen F₁, F₂ und F.
• Fig. 4 den Flächenbrechwert in perspektivischer Dar­stellung, und
• Fig. 5 den Flächenastigmatismus in perspektivischer Darstellung.

The invention is described below using an exemplary embodiment with reference to the drawing, in which:

• 1 shows the refractive index of a spectacle lens according to the invention along the main meridian,
• 2.01 to 2.17 the radii of curvature of horizontal sections as a function of the distance from the main meridian,
• Fig. 3 shows the change in the maximum value of the functions F₁, F₂ and F.
• 4 shows the surface power in perspective, and
• Fig. 5 shows the surface astigmatism in perspective.

Description of an embodiment

In the exemplary embodiment described below, the front surface is designed as a progressive surface without restricting the general inventive concept. The progressive surface has a flat main meridian; in other words, the main meridian is a plane curve.

The coordinate system is chosen so that the Y axis lies in the plane (x = 0), which also contains the main meridian.

Fig. 1 shows the course of the refractive index in dioptrine (dpt) along the main meridian, i.e. along the y axis. As can be seen in FIG. 1, the surface power transfers to the main meridian in the far part FT about 4.5 dpt; in the progression zone PZ the refractive index increases on the main meridian by 3 D, so that it is about 7.5 D in the near part NT; the exemplary embodiment shown thus has a base curve of 4 dpt and an addition A of 3 dpt.

Furthermore, the lower limit of the distant part FT, which is approximately y = 4 mm, and the upper limit of the near part NT, which is approximately y = -12 mm, between which the actual progression zone PZ extends are shown in FIG. 1.

2.01 to 2.17 show the course of the radii of curvature of horizontal sections, ie the section curves of the progressive surfaces with planes y = const. depending on the coordinate x, ie the distance from the main meridian. The difference Δrh of the curvature is in the figures radius rh (x) for a specific x value and the radius of curvature rh (0) for the value x = 0.

The absolute values are not shown in the figures, but they are determined by the condition that the astigmatism on the main meridian should have a certain value. In the exemplary embodiment shown, the surface astigmatism on the main meridian in the far part FT and in the near part NT (within the scope of the manufacturing tolerances) is zero and reaches a maximum value of 0.2 dpt in the progression zone PZ, but it is of course also possible for the main meridian to be completely as a navel line train or allow a larger maximum value of astigmatism along the main meridian.

By abandoning the requirement that the main meridian should be a navel line, in which the radii of curvature of the main sections must be of the same size, there is greater freedom in the design of the progressive surfaces through which an improvement in the correction can be achieved without the slight astigmatism on the main meridian would be disruptive for those wearing glasses.

As can be seen from FIGS. 2.01 to 2.03, the radius of curvature rh initially decreases with increasing distance x from the main meridian and then remains constant over a larger area before it increases again.

From about y = 20 mm (Fig. 2.04) there is an intermediate maximum in the course of the radius of curvature at x = 18 to 20 mm, which increases rapidly with decreasing y values (Fig. 2.05 to 2.08). At the lower edge of the distance part FT (y = 4 mm) the radius of curvature increases in the vicinity of the main meri dians still in the range x = 18 to 20 mm, in which the intermediate maximum occurred at larger y values, there is now a maximum value at which the radius of curvature is already greater than the value of the radius of curvature on the main meridian (Fig. 2.08). With even larger x values, however, the radius of curvature decreases again to values that are smaller than the radius of curvature on the main meridian.

When entering the progression zone PZ, the radius of curvature is initially almost constant in the vicinity of the main meridian and then reaches a maximum value in the area x ≈ 20 mm (Fig. 2.08), which increases rapidly with decreasing y values and in the lower area of the progression zone PZ or in the upper area of the near part, values which differ by more than 100 mm from the radius of curvature on the main meridian (Fig. 2.10 following).

As the y values continue to decrease, the difference between the maximum radius of curvature, which for each horizontal section is further at x values between approximately 18 mm and 20 mm, decreases again (Fig. 2.13 f).

This course of the radii of curvature rh (x) of horizontal sections as a function of the distance x from the main meridian, shown in FIGS. 2.01 to 2.17, is a consequence of the surface structure according to the invention:

According to the invention, the course of the curvature change Δrh = r (x, y) - r (0, y) of horizontal sections (y = const.) As a function of the distance from the main meridian through the superposition of two functions F₁ (x, y) and F₂ (x , y) given:
Δrh = F (x, y) = F₁ (x, y) + F₂ (x, y)

According to the first function F 1 (x, y), the radius of curvature in the exemplary embodiment shown, in which the progressive surface is the front surface, initially increases and reverses again at a distance from the main meridian of approximately 20 mm. According to the second function F₂ (x, y), the radius of curvature initially decreases, the change in the radius of curvature also reversing at a distance which in turn is approximately 20 mm from the main meridian.

According to the invention, the functions F 1 and F 2 are topologically the same for all horizontal sections, but the absolute values of the amplitudes of the two functions change in opposite directions along the main meridian.

Figs. 3 shows the change in the maximum value of the functions F 1 and F 2 as a function of y. The boundaries of the distant part FT, the progression zone PZ and the near part NT are again shown in FIG. 3. As can be seen in Fig. 3, the maximum value of the function F 1 reaches a maximum in the lower region of the progression zone and then rapidly decreases to a very small value in the region of the distant part. The function F₂, on the other hand, has a maximum value in the far section and already decreases in the middle part of the progression zone PZ to such small values that it is no longer effective in comparison to the function F₁. Even in the far part, the maximum value of the function F₂ is small compared to the maximum value of the function F₁, but significantly larger than the value of the function F₁ with the same y values.

In Fig. 3, the maximum amplitude of the function F = F₁ + F₂ is also drawn, which results from the superposition of the two functions.

4 and 5 show in a perspective representation the course of the surface refractive index and of the surface astigmatism for the spectacle lens according to the invention shown in FIGS. 1 to 3.

As can be seen in FIG. 4, the lines of the same refractive index run approximately horizontally in the region of the progression zone near the main meridian, so that the spectacle wearer receives a pleasantly uniform increase in progression even if the gaze is not lowered exactly along the main meridian.

FIG. 5 shows that the surface astigmatism in the lateral edge areas achieves values similar to that of glasses of comparable addition, which belong to the prior art, but that the change in the surface astigmatism is comparatively small; in other words, the "mountain range", which represents the surface astigmatism in perspective, is far less "jagged" than in comparable known spectacle lenses, i.e. Spectacle lenses with the same base curve and the same addition.

The invention has been described above using an exemplary embodiment without restricting the general inventive concept, which can be gathered in particular from the claims.

The embodiment shown has a base curve of 4 D and the addition of 3.0 D; a refractive index n = 1.604 is also used. Of course, when using the basic ideas according to the invention, the same advantage as in the described exemplary embodiment is also obtained with other basic curves, additions and refractive indices. In particular, it is possible to manufacture the spectacle lens according to the invention from a plastic material with a refractive index of 1.50 or a glass with a refractive index of 1.525 or 1.7.

Furthermore, in the exemplary embodiment shown, the main meridian is a flat curve. The basic idea according to the invention of constructing the spectacle lens by superimposing two functions can, however, also be applied to spectacle lenses in which the main meridian is a sinuous curve which follows the main line of sight, i.e. the line of the points of penetration of the optic rays when the eye is lowered. The form of such main meridians is known from the literature, so that there is no need to go into further detail here.

However, the surface design according to the invention also leads to such a wide progression zone and such a wide vicinity in the case of a flat main meridian that a deviation of the main line of sight from the main meridian does not lead to disturbing aberrations for the spectacle wearer.

Of course, it is possible to grind the eyeglass lens according to the invention in a known manner pivoted into an eyeglass frame and / or to manufacture the lens decentrally; this means that the main meridian does not run through the geometric center of the tubular glass.

It is particularly possible to calculate the glass in the "position of use", ie not only to include the astigmatism of oblique bundles in the corrector, but also to take into account any "horizontal symmetries" in the position of use. Here too, reference is made to the relevant literature.

The described embodiment is a spectacle lens for normal applications, in which emphasis is placed on a comparatively large distance part and a near part located underneath.

The basic ideas of the invention can, however, also be applied to spectacle lenses in which the near part is to be comparatively large and the far part is to be comparatively small; the near part can also be located above the distant part, for example, as is often required for special glasses such as pilot or screen glasses.

Claims (12)

1. Progressive spectacle lens, in which at least one surface contributes to the increase in effectiveness from the far part (FT) via the progression zone (PZ) to the near part (NT), and in which the radii of curvature (rh) of the intersection curves (horizontal sections) of the surface or surfaces contributing to the increase in effect decrease with horizontal planes (y = const) as a function of the distance from the main meridian at the front surface in the area of the main meridian in the distant part and increase in the near part and increase with the eye surface in the far part and decrease in the near part, and the course of the change in curvature (Δrh = rh (x, y) -rh (0, x)) reverses with increasing distance (x) from the main meridian,
characterized by the combination of the following features:
- The course of the change in curvature (Δrh) of the horizontal sections (y = const.) with increasing distance (x) from the main meridian is given by the superposition of two functions F₁ (x, y) and F₂ (x, y):
Δrh = F (x, y) = F₁ (x, y) + F₂ (x, y)
- According to the first function F 1 (x, y), the radius of curvature initially increases on the front surface or decreases on the surface on the eye side, the change in the radius of curvature being reversed at a distance of 14 to 26 mm from the main meridian,
- According to the second function F₂ (x, y), the radius of curvature initially decreases on the front surface or on the surface on the eye side, the change in the radius of curvature being reversed at a distance of 14 to 26 mm from the main meridian,
- the absolute values of the amplitudes of the two functions change along the main meridian at least in the progression zone,
- at least in the area of the distance section, the following applies to a stripe to the left and right of the main meridian:
δF₂ / δx (x = x _o , y = y _o )> δF₁ / δx (x = x _o , y = y _o
where δF _i / δx is the first derivative of the function F _i from x. 2. spectacle lens according to claim 1,
characterized gkennzeichnet that the amplitude of the second function in the distance portion and in the near portion is maximum ≈ 0th 3. spectacle lens according to claim 1 or 2,
characterized in that the amplitude of the first function initially increases from the lower edge of the spectacle lens to a maximum value in the region of the upper limit of the near part (NT) and then decreases to a value> 0 in the region of the far part. 4. spectacle lens according to one of claims 1 to 3,
characterized in that the radius of curvature (rh) of horizontal sections in the upper region of the distant part is almost constant between a distance (x) of approximately 10 mm and 25 mm from the main meridian. 5. spectacle lens according to one of claims 1 to 4,
characterized in that the ratio of the absolute values of the maximum amplitudes of the first and second functions is greater than 10: 1. 6. spectacle lens according to claim 5,
characterized in that the ratio of the absolute te of the maximum amplitudes of the first and second functions is between 15: 1 and 25: 1. 7. spectacle lens according to one of claims 1 to 6,
characterized in that no horizontal section has even approximately constant radii of curvature. 8. spectacle lens according to one of claims 1 to 7,
characterized in that the radii of curvature of horizontal sections in the progression zone initially become smaller and then larger than on the main meridian or initially larger and then approximately the same size as on the main meridian with increasing distance (x) from the main meridian. 9. spectacle lens according to one of claims 1 to 8,
characterized in that the distance of the point from the main meridian, at which the change in curvature reverses according to the first function, decreases in the direction of the lower edge of the spectacle lens. 10. spectacle lens according to one of claims 1 to 9,
characterized in that the spectacle lens has no spherically formed area. 11. spectacle lens according to one of claims 1 to 10,
characterized in that the main meridian of the area or areas contributing to the increase in action is flat. 12. Spectacle lens according to one of claims 1 to 11,
characterized in that the area astigmatism on the main meridian in the far part and in the near part is about 0 dpt and does not exceed a value of 0.5 dpt in the progression zone.

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